1. Field of the Invention
The present invention relates to a CCD type solid state imaging device and more particularly, to a novel CCD type solid state imaging device which is capable of improving the vertical charge transfer efficiency and the efficiency of reading out signal charges from the light receiving elements to the transfer channels.
2. Description of the Related Art
The conventional CCD type solid state imaging device has vertical charge transfer electrodes arranged such that the orientation of the boundary lines among multilayer vertical charge transfer electrodes lying over the transfer channels is normal to the charge transfer direction. In other words, the vertical transfer electrodes of the CCD imaging device represent, as a whole, a shape which would be formed by a plurality of rectangles if they were shifted parallelly so as to partially overlap one another with the horizontal sides of each of the vertical charge electrodes running normal to the transfer direction as will be described in detail later.
However, in view of the fact that it is considered necessary for a CCD type solid state imaging device to have a higher charge transfer efficiency, an attempt has been made to improve the charge transfer efficiency in such a manner that a shallow barrier of an oblique pattern is formed by selectively implanting impurities in the transfer channels thereby meeting such demand but this method is not desirable since it reduces the amount of electrical charges being handled, in proportion to the area of the barrier.